Direct-Drive 3D Printer Extruder Eliminates Backlash
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Solution Overview
Problem
Conventional 3D printing systems face challenges with backlash and precision control in the relative three-axes movement of the print head, particularly when dealing with complex geometries and parts with moving components, due to high backlash in the drivetrain and limitations in axial stiffness and print speed.
Innovation Solution
The apparatus employs a movable dispensing head with a flexible strand of thermoplastic resin material, heated to a temperature just above its solidification point, and a material advance mechanism with roller pairs and a speed-controlled driver motor to regulate the flow rate, minimizing backlash and improving precision through controlled movement and material dispensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a Bowden extruder with separate motor assembly and PTFE tube is used, then the print head can be moved in three dimensions, but high backlash occurs due to gap between filament and tube, filament compression spring effect, slop in tube end retention, and axial tube distortion
Solution Approach 1:
The patent combines the extruder motor assembly with the print head into a single integrated unit, eliminating the PTFE tube connection and its associated backlash problems. The motor, feed gear, and print head are mounted together on the moving carriage, creating a direct-drive system that removes the flexible tube linkage entirely.
Solution Approach 2:
The patent removes the PTFE tube and its retention mechanisms from the system by implementing direct filament feeding. The filament is fed directly from the spool into the print head without passing through a flexible tube, eliminating the source of backlash caused by tube gaps, compression, and distortion.
2Force
If a stiff PTFE tube is used to counteract pushing force, then material can be delivered to the print head, but axial stiffness is limited and friction increases
Solution Approach 1:
The patent eliminates the PTFE tube entirely by implementing direct filament feeding. The filament is pushed directly into the print head without passing through a tube, removing the compromise between stiffness and friction that limited previous designs.
3Ease of operation
If conventional Bowden extruder is used, then material can be fed through flexible tube, but print speed is limited due to filament compression and relaxation effects causing material buildup during deceleration and thinning during acceleration
Solution Approach 1:
The patent merges the extruder motor assembly with the print head into a single integrated unit mounted on the moving carriage. This direct-drive configuration eliminates the flexible tube linkage that caused compression and relaxation effects, enabling higher print speeds without material inconsistency.
Solution Approach 2:
The patent removes the PTFE tube and its associated compression spring effects from the system. By feeding filament directly into the print head without a flexible tube intermediary, the system eliminates the compression-relaxation cycles that limited print speed and caused material buildup or thinning.
4Device complexity
If separate motor assembly with feed gear and PTFE tube is used, then extruder can be mounted remotely, but slop in drivetrain results in poor performance at start and stop points
Solution Approach 1:
The patent combines the extruder motor assembly with the print head into a single integrated unit. The motor, feed gear, and print head are mounted together on the moving carriage, creating a direct-drive system that eliminates drivetrain slop and achieves precise start and stop control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances the precision and speed of 3D printing by reducing backlash and filament compression effects, enabling the creation of complex geometries and parts with improved accuracy and reduced material inconsistencies.
Implementation Method 1
heated relatively rapidly to a temperature just above its solidification temperature
Implementation Method 2
solidifies by cooling to a solidification temperature
Implementation Method 3
The modeling material thermally solidifies after it is deposited
Data Source
AI summary
An apparatus for making three-dimensional objects comprises a movable dispensing head to dispense in a fluid state a supply of flexible strand of thermoplastic resin material. Two motors are provided for moving said dispensing head relative to a base member in an x, y plane in a predetermined sequence and pattern. A heater heats flexible strand to a predetermined temperature above the solidification temperature of said material.